21136456 has 32 divisors (see below), whose sum is σ = 43505280. Its totient is φ = 9547200.

The previous prime is 21136441. The next prime is 21136463. The reversal of 21136456 is 65463112.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15265 + ... + 16591.

It is an arithmetic number, because the mean of its divisors is an integer number (1359540).

Almost surely, 2^21136456 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21136456, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21752640).

21136456 is an abundant number, since it is smaller than the sum of its proper divisors (22368824).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21136456 is a wasteful number, since it uses less digits than its factorization.

21136456 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1525 (or 1521 counting only the distinct ones).

The product of its digits is 4320, while the sum is 28.

The square root of 21136456 is about 4597.4401573049. The cubic root of 21136456 is about 276.4887021817.

Adding to 21136456 its reverse (65463112), we get a palindrome (86599568).

The spelling of 21136456 in words is "twenty-one million, one hundred thirty-six thousand, four hundred fifty-six".